1. Field of the Disclosure
This disclosure relates generally to devices, systems and methods for positioning and using equipment used in connection with the drilling, completion and/or workover of oilfield wells.
2. Description of the Related Art
Valuable hydrocarbon deposits, such as those containing oil and gas, are often found in subterranean formations located thousands of feet below the surface of the Earth. To recover these hydrocarbon deposits, boreholes or wellbores are drilled by rotating a drill bit attached to a drilling assembly, also referred to herein as a “bottom hole assembly” or “BHA.” Such a drilling assembly is attached to the downhole end of a tubing or drill string made up of jointed rigid pipe or a flexible tubing coiled on a reel (“coiled tubing”). For directional drilling, the drilling assembly can use a steering unit to direct the drill bit along a desired wellbore trajectory.
These drilled wellbores, which can include complex three-dimensional trajectories, intersect various formations of interest. During drilling and in later completion activities, success or failure of effectively producing hydrocarbons from a given formation can hinge on precisely measuring the depth of a given formation and precisely positioning a wellbore tool at a depth corresponding to a given formation. In some instances, a hydrocarbon bearing zone can be only a meter or so in depth. Thus, the positioning of wellbore tools such as a perforating gun or a kickoff for a lateral bore must be positioned well within that one meter range.
Conventional depth measurement systems utilize surface-based equipment and techniques for determining a measured depth of a downhole tool, such as a bottomhole assembly. Conveyance devices, such as drill pipe or wirelines, that used to convey downhole tooling are susceptible to stretching during deployment. Because these conveyance devices can span hundreds of meters or more, the elongation of the conveyance device may significantly impact surface depth measurements. That is, for instance, a surface measurement may indicate that a downhole tool is at 800 meters, whereas, due to factors such as tensile loading, the tool is actually at 840 meters. Thus, surface measurements may not provide the accuracy needed to position wellbore equipment within a narrow zone of interest, e.g., within a tolerance of a half-meter. The present disclosure is directed to methods and devices for accurately positioning wellbore tooling as well as methods and devices for enhancing wellbore operations.